The present invention relates to an equilibrium apparatus of cut-off mechanism for high-speed nut former, and more particularly to one which can promote the stability of the cut-off mechanism so as to increase the cutting speed thereof.
Generally, a conventional nut former, as shown in FIG. 1 which is a schematic top view thereof, includes a power mechanism 10 such as an electric motor which serves as a power source; a crank shaft 11 drivable by the power mechanism 10 to rotate; a punch rod 12 drivable by the intermediate crank arm to operate; a punch plate 13 connected movably to the punch rod 12 so that it can be driven by the punch rod 12 to effect straight reciprocating motion of pressure stamping; an end crank arm 14 with a crank pin connected pivotally to a connecting rod 15; and a cut-off mechanism 20 including a slide plate 21 connected movably to the connecting rod 15 so as to effect horizontal straight reciprocating motion. The horizontal straight reciprocating motion of the slide plate 21 causes the cutting tool (not shown) to effect vertical straight reciprocating motion, to thus cut a steel wire extending from a winch 16 into steel masses to be pressure stamped.
FIG. 2 is a schematic top elevational detail view of the conventional cut-off mechanism. FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2.
Referring to FIGS. 2 and 3, the conventional cut-off mechanism 20 includes:
a push plate 22 connected securely to the slide plate 21 and having a push surface which has a convex portion 220 and a concave portion 221;
a cutting unit 23 including a driven piece 230 having two projections 230a and 230b forming a gap therebetween opposite the push surface of the push plate 22, a cutting tool connecting rod 231 secured to the driven piece 230, a roller 232 mounted movably on the driven piece 230 within the gap and always abutting on the push surface of the push plate 22, and two extension rods 233 respectively extending from the projections 230a and 230b; and
a pair of compression springs 24 disposed on the outer end portions of the extension rods 233 between the machine table A and rings 241 which are positioned by nuts 240 screwed to the extension rods 233.
In addition, a clamp 25 is integral with the driven piece 230 in order for clamping the nuts. Since the clamp 25 is not the improvement of the present invention, more detailed description will be omitted for the purpose of simplicity.
In use, when the roller 232 is moved onto the convex portion 220 of the push surface, the driven piece 230 is pushed upwardly. Thus, the cutting tool cuts the steel wire off, while the rings 241 compress the compression springs 24.
Subsequently, when the roller 232 is moved onto the concave portion 221 of the push surface, the driven piece 230 moves back to its lowermost position. Thus, the compression spring 24 is restored to its uncompressed condition, and the cutting tool moves away from the steel wire.
It has been understood that the conventional cut-off mechanism 20 generally suffers from the following disadvantages:
(1) Poor stability. Since the driven piece 230, the cutting tool and its connecting rod 231, and the extension rods 233 are simultaneously moved at a relatively high speed in a single direction, the entire machine table A will be subjected to serious shock which will ultimately affect the cutting operation of the steel wire.
(2) High rate of malfunction. The speed of the extension rods 233 is relatively high, so the elasticity of the compression springs 24 is easily fatigued. Also, the serious shock suffered by the machine table A frequently causes the parts of the mechanism to malfunction.
(3) Low production rate. To ensure the quality of the product and the long lifetime of the cut-off mechanism, the cutting speed of the cut-off mechanism must be reduced.
(4) Excessive use of power. Since the push plate 22 must bear the weight of the roller 232, the driven piece 230, the extension rods 232, and the restoring force of the compression springs 24, a great deal of power is necessary. The manufacturing cost is thus increased.
(5) Difficult to test. In inching test, it is necessary for the push plate 22 to bear both the shearing force of cutting the steel wire off and the restoring force of the compression springs 24.